Reactive oxygen species that can be scavenged or whose formation can be inhibited by flavonoids
| O⨪2(Superoxide anion) | One-electron reduction product of O2. Produced by phagocytes, formed in autoxidation reactions (flavoproteins, redox cycling), and generated by oxidases (heme proteins). |
| HO⨪2 (Perhydroxy radical) | Protonated form of O⨪2 |
| H2O2 (Hydrogen peroxide) | Two-electron reduction product of O2 formed from O⨪2(HO⨪2) by dismutation or directly from O⨪2. Reactivity of O⨪2 and H2O2 is amplified in the presence of heme proteins. |
| OH (Hydroxyl radical) | Three-electron reduction product of O2 generated by Fenton reaction, transition metal (iron, copper)-catalyzed Haber-Weiss reaction; also formed by decomposition of peroxynitrite produced by the reaction of O⨪2 with NO· (nitric oxide radical). |
| RO⋅ (Alkoxyl radical) | Example: Lipid radical (LO⋅). |
| ROO⋅ (Peroxyl radical) | Example: Lipid peroxy radical (LOO⋅) produced from organic hydroperoxide (e.g. lipid hydroperoxide, LOOH), ROOH by hydrogen abstraction. |
| 1O2 | Singlet oxygen. |